A key factor in modern democracies’ legitimisation is the extent to which policies submitted for public approval before an election translate into material outcomes once a political party has won power. Current research finds no clear empirical evidence for partisanship in policy-making nor has any unified theory been offered or tested systematically. This article addresses that gap by offering a conditional approach to policy-making undertaken by parties in government. It suggests that partisan influence on policy depends on both office-holders’ capacity for implementing policies evoked during their electoral campaigns and on governing parties’ incentives to implement electoral promises. Data from French Agendas Project datasets is used to compare the contents of governing parties’ pre-election manifestos with legislation passed in France between 1981 and 2012. Panel negative binomial regressions on electoral and legislative agendas support the expected outcome, namely that issues featuring in governing parties’ electoral manifesto have had an impact on their subsequent legislative agendas, with the effect depending on both partisan capacities and incentives. Party programmes do matter in policy-making, albeit only under certain conditions.